The first step in developing BCAs is the isolation and screening process (Droby et al., 2009), and the best sources of antagonistic microorganisms are their natural environments in which they compete with plant pathogens (Janisiewicz and Korsten, 2002). The second step is to clarify the mechanism of action, as well as the understanding of biocontrol systems represents a crucial point to know the interactions among environment, pathogen and BCA and, therefore, the expected biocontrol efficacy.